A workpiece is supported by work support means (40; 40'; 40''; 44'; 142, 144) for movement in a first direction by co-operating workpiece clamping and feeding means (46; 142, 144), both said means being supported on a carriage (16) for movement in a second direction normal to the first to move a workpiece relative to a sewing machine head. Both of said means are arranged on both sides of an elongated aperture (42) extending in the second direction in alignment with a needle penetration point (N). Stepping motors (24; 60) are provided for moving the carriage (16) and operating the workpiece clamping and feeding means (46; 142, 144) under programmed control. A camera (70) is also provided aligned with the aperture (42), for detecting the peripheral outline of a workpiece fed therebeneath. Computer means is effective, in response to the detected outline, to identify the workpiece type and its orientation and location on the workpiece support means and accesses an appropriate stitch pattern data file and modifies the data to take account of the workpiece orientation and location. The workpiece is then sewn according to the thus modified data.